Long-term flood-hazard modeling for coastal areas using InSAR measurements and a hydrodynamic model: The case study of Lingang New City, Shanghai

Abstract

In this paper, we study long-term coastal flood risk of Lingang New City, Shanghai, considering 100-and 1000-year coastal flood return periods, local seal-level rise projections, and long-term ground subsidence projections. TanDEM-X satellite data acquired in 2012 were used to generate a high-resolution topography map, and multi-sensor InSAR displacement time-series were used to obtain ground deformation rates between 2007-2017. Both data sets were then used to project ground deformation rates for the 2030s and 2050s. A 2-D flood inundation model (FloodMap-Inertial) was employed to predict coastal flood inundation for both scenarios. The results suggest that the sea-level rise, along with land subsidence, could result in minor but non-linear impacts on coastal inundation over time. The flood risk will primarily be determined by future exposure and vulnerability of population and property in the floodplain. Although the flood risk estimates show some uncertainties, particularly for long-term predictions, the methodology presented here could be applied 2 to other coastal areas where sea level rise and land subsidence are evolving in the context of climate change and urbanization.

Flood Risks in Sinking Delta Cities: Time for a Reevaluation?

“…We apply a Differential Synthetic Aperture Radar Interferometry (DInSAR)-based geotechnical model developed by Pepe et al (2016), Yin et al (2019), and Zhao et al (2015) to predict the cumulative deformation of seawall (i.e., sea dike) along the Shanghai coastline. First, we use multitemporal and multisatellite synthetic aperture radar (SAR) images to retrieve the seawall deformation history and rates in Shanghai.…”

“…A full description of the model structure and parameterization can be found in Yu and Lane (2011). FloodMap-Inertial, as well as its earlier diffusion-based version (FloodMap) (Yu & Lane, 2006), have been tested and implemented in fluvial, pluvial, and coastal environments in Shanghai (Yin et al, 2013(Yin et al, , 2015(Yin et al, , 2019, achieving a good level of performance for flood prediction. A recent validation study (Yin et al, 2016), comparing model output against observed inundation in New York City, further indicated that the city-scale and street-level modeling framework similar to that used here is capable of high predictive skill for inland flooding.…”

“…While providing protection against low probability floods, artificial dikes may fail due to a combination of high water loading, wave attack, and/or long flood duration (Vorogushyn et al, 2010). Dike failure can also occur as a result of long‐term structure deformation, the magnitude of which can be much greater than hinterland subsidence in delta cities, such as New Orleans and Shanghai (Dixon et al, 2006; Yin et al, 2019). Among various failure mechanisms, dike breach or flow over the crest of dikes are the two major modes causing significant hinterland inundation and damages.…”

Integrated Analysis of the Combined Risk of Ground Subsidence, Sea Level Rise, and Natural Hazards in Coastal and Delta River Regions

“…Other mechanisms related to sea level changes include friction-altering changes in water depth, resonance changes in harbor regions [56], or stratification changes induced by increased upper-ocean warming [8], which may modify internal tides [57]. On a shorter timescale, seasonal tidal variations can be due to rapid changes in water column stratification or by seasonal river flow characteristics [18]. The high sensitivity of tides relative to sea level changes also suggests increased impacts of storm-induced flooding since both tides and storm surge are long-wave processes [56,58].…”

“…The principal results of the investigations performed within our Dragon IV project have been published in peer-reviewed journals over the last five years [14][15][16][17][18][19][20][21][22][23][24][25][26][27] and represent the starting point for future studies to be performed in the following years. We will summarize the main results of previous research related to this project in this article.…”